# NEAR INFRARED MEASUREMENTS OF VOLATILE ORGANIC COMPOUNDS USING DIODE LASER CAVITY RINGDOWN SPECTROSCOPY

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 Title: NEAR INFRARED MEASUREMENTS OF VOLATILE ORGANIC COMPOUNDS USING DIODE LASER CAVITY RINGDOWN SPECTROSCOPY Creators: Scherrer, Susan T.; Wang, Chuji; Winstead, Christopher B. Issue Date: 2005 Publisher: Ohio State University Abstract: Absorption cross-sections of the C-H stretching overtones of benzene, chlorobenzene, 1,2-dichlorobenzene, and toluene have been measured in the NIR (5970 to 6135 cm$^{-1}$) using CW-Cavity Ringdown Spectroscopy. The wavelength-dependent absorption cross-sections were obtained with both an external cavity diode laser and a free space DFB diode laser. Low-pressure samples (0.01 to 2.0 Torr) were introduced into an evacuated cavity. The experimental room temperature absorption cross-sections obtained for these four volatile organic compounds were found to vary in intensity from approximately are 1.2 x $10^{-22}$ to 6.9 x $10^{-21}$ cm $^{2}$, depending on the wavelength and molecular structure. The substitution of 1 or 2 Cl atoms causes a spectral shift to the blue relative to the benzene peak, whereas the substitution of a methyl group causes a red shift. Description: Author Institution: Diagnostic Instrumentation and Analysis Laboratory, Mississippi State University, Starkville, MS 39759; Department of Physics and Astronomy, University of Southern Mississippi, Hattiesburg, MS 39406 URI: http://hdl.handle.net/1811/30311 Other Identifiers: 2005-MF-04